Expandable scaffold with wheel lock

ABSTRACT

A scaffold includes two or more legs and an expandable platform assembly having at least two shelves. At least one of the shelves slides in a lengthwise direction in relation to the others.

TECHNICAL FIELD

The present disclosure relates to a maneuverable, expandable scaffoldstructure.

BACKGROUND

Construction projects often call for the use of scaffolding. Scaffoldstend to be cumbersome structures, with a length and height determined bythe demands of the job. Scaffolding may comprise fixed-sized platformsthat are assembled with vertical supports and rails on the site. Thiscreates a problem when different lengths of platform are needed (forexample, one length for longer walls, and a shorter length for shorterwalls). U.S. Pat. Nos. 6,109,391, 5.031,722, 3,491,852, and 2,910,135describe such scaffolds.

A pre-constructed scaffold may be used, having a fixed platform length.The pre-constructed scaffold may ride on wheels. Again, a problem withfixed-length pre-constructed scaffolds arises in situations wheredifferent lengths of platform are needed.

Various types of expandable scaffolds exist, particularly for use insidelarge storage vessels. These scaffolds are designed to collapse and fitthrough doorways, then to be expanded once they are inside the storagevessels. U.S. Pat. No. 5,533,592 is an example of such a scaffold. Oncein place, the platform length is fixed.

Various types of extendable scaffolds exist, particularly for mountingon vehicles and providing an adjustable scaffold height. U.S. Pat. No.4,060,148 is an example of such a scaffold. Although the height of thescaffold is adjustable, the platform length is not.

SUMMARY

The following summary is intended to highlight and introduce someaspects of the disclosed embodiments, but not to limit the scope of theinvention. Thereafter, a detailed description of illustrated embodimentsis presented, which will permit one skilled in the relevant art to makeand use aspects of the invention. One skilled in the relevant art canobtain a full appreciation of aspects of the invention from thesubsequent detailed description, read together with the figures, andfrom the claims (which follow the detailed description).

A scaffold includes an expandable platform assembly supported by legs.The platform assembly has at least two shelves. At least one of theshelves slides in a lengthwise direction in relation to the others. Atleast one leg of the scaffold includes a rod and a spring to urge therod through an aperture in a caster and into contact with a wheel. Theaperture is formed to pass the rod in limited orientations of the rodwith respect to the caster.

BRIEF DESCRIPTION OF THE DRAWINGS

The headings provided herein are for convenience only and do notnecessarily affect the scope or meaning of the claimed invention.

In the drawings, the same reference numbers and acronyms identifyelements or acts with the same or similar functionality for ease ofunderstanding and convenience. To easily identify the discussion of anyparticular element or act, the most significant digit or digits in areference number refer to the figure number in which that element isfirst introduced.

FIG. 1 is an illustration of an embodiment of an expandable scaffold.

FIG. 2 is an illustration of an embodiment of an expandable scaffoldplatform assembly.

FIG. 3 is a bottom view illustration of an embodiment of an expandablescaffold platform rail assembly.

FIG. 4 is an illustration of an embodiment of an upper shelf of anexpandable scaffold platform assembly.

FIG. 5 is a side view illustration of an embodiment of an upper shelf ofan expandable scaffold platform assembly.

FIG. 6 is a side view illustration of an embodiment of an expandablescaffold platform rail assembly.

FIG. 7 is a cut-away front view illustration of an embodiment of anexpandable scaffold platform rail assembly.

FIG. 8 is an illustration of an embodiment of a leg assembly of anexpandable scaffold.

FIG. 9 is an illustration of an embodiment of a leg assembly including awheel lock.

FIG. 10 is a cut away top view illustration of an embodiment of a wheellock.

FIG. 11 is a cut away top view illustration of another embodiment of awheel lock.

FIG. 12 is an illustration of an embodiment of an expandable safety railassembly.

DETAILED DESCRIPTION

The invention will now be described with respect to various embodiments.The following description provides specific details for a thoroughunderstanding of, and enabling description for, these embodiments of theinvention. However, one skilled in the art will understand that theinvention may be practiced without these details. In other instances,well known structures and functions have not been shown or described indetail to avoid unnecessarily obscuring the description of theembodiments of the invention. References to “one embodiment” or “anembodiment” do not necessarily refer to the same embodiment, althoughthey may.

FIG. 1 is an illustration of an embodiment of an expandable scaffold.The scaffold comprises a platform assembly 116, leg assemblies 118including ladder assemblies 114, and at least one safety rail assembly112. The platform assembly 116 provides a place for workers to stand;the safety rail assembly 112 helps prevent workers from falling; theladder assemblies 114 provide a way up to and down from the platformassembly 116; and the leg assemblies 118 support the other assembliesabove the ground.

FIG. 2 is an illustration of an embodiment of an expandable scaffoldplatform assembly 116. Expansion capability is provided by a lower shelf202 that slides, in a telescoping fashion, in a lengthwise directionwith respect to an upper shelf 204. Telescoping enables the platformlength to be expanded or contracted, without causing the platform lengthto differ from the distance between the ladder assemblies 114. At leastone inner rail 211 of the lower shelf 202 slides into at least one outerrail 212 of the upper shelf. A shelf transition 208 alleviates theabruptness of the edge between the upper shelf 204 and lower shelf 202.A slide lock 206, when engaged, prevents the sliding action of the uppershelf 204 with respect to the lower shelf 202. The platform assembly 116may comprise one or more retractable supports 216 to provide support forconstruction materials, such as sheets of drywall or plywood. Safetyrail retainers 214 receive posts to support the safety rail assembly112.

FIG. 3 is a bottom view illustration of an embodiment of an expandablescaffold platform rail assembly. The inner rail 211 slides within theouter rail 212. A flange 308 of the outer rail 212 supports the uppershelf 204, and a flange 310 of the inner rail 211 supports the lowershelf 202. The flange 310 of the inner rail 211 may engage the lowershelf 202 to prevent lateral motion and shear motion of the lower shelf202. A stop 316 of the outer rail 212 engages a stop 318 of the innerrail 211 to prevent the inner rail 211 from coming completely free ofthe outer rail 212. A lock hole 314 of the outer rail 212 aligns withlock holes 306 of the inner rail 211. Insertion of a pin through thelock holes prevents the inner rail 211 from sliding within the outerrail 212, hence preventing the upper shelf 204 from sliding with respectto the lower shelf 202.

FIGS. 4 and 5 are illustrations of an embodiment of an upper shelf 204of an expandable scaffold platform assembly. The shelf transition 208 isfixed to the upper shelf 204 and provides a graded transition betweenthe upper shelf 204 and the lower shelf 202. This may reduce thelikelihood of injuries from tripping on the abrupt edge that mayotherwise result between the upper shelf 204 and lower shelf 202.

FIG. 6 is a side view illustration of an embodiment of an expandablescaffold platform rail assembly. A slide lock 206 comprises a housing606 and a locking pin 602. In an unlocked position shown, the spring 604is under compression and the locking pin 602 does not pass through thelock hole 314 of the outer rail 212 and one of the lock holes 306 of theinner rail 211. In this position the locking pin 602 may engage thehousing 606 in a manner that prevents the spring 604 from urging thelocking pin 602 toward the rails. For example, the locking pin 602 maybe secured within a slot of the housing 606.

When the locking pin 602 is not secured in the unlocked position shown,the spring 604 may urge the locking pin 602 toward the rails.

When the lock hole 314 of the outer rail 212 is aligned with one of thelock holes 306 of the inner rail 211, the locking pin 602 may be urgedthrough the holes, preventing the inner rail 211 from sliding within theouter rail 212.

FIG. 7 is a cut-away front view illustration of an embodiment of anexpandable scaffold platform rail assembly. The locking pin 602 is shownin the locked position. The outer rail 212 is formed to comprise aflange 308 and a gap 702. The flange 310 of the inner rail, comprising aplurality of platform stabilizer posts 312, extends beyond the gap 702,and provide a stable supporting surface for the lower shelf 202. Theposts 312 may protrude through holes in the lower shelf 202 to providestabilization against lateral motion and shear. A stop 318 of the innerrail 211 contacts a stop 316 of the outer rail 212 when the platformassembly 116 is at full extension.

FIG. 8 is an illustration of an embodiment of a leg assembly of anexpandable scaffold. A leg 802 provides support for the scaffold. Asleeve 804 slides over the leg, and acts as a moveable mount for aspring 808 loaded lock pin 806. The height of the platform assembly 116may be set by adjusting the position of the sleeve 804 on the leg, andthen secured by setting the lock pin 806 through holes in the sleeve 804and the leg 802. The scaffold may comprise four legs 802, each having asleeve 804. The sleeves 804 on one end of the scaffold may be coupled tothe outer rail 212 of the platform assembly 116, and the sleeves 804 onthe other side of the platform assembly 116 may be coupled to the innerrail 211 of the platform assembly 116. The outer rail 212 and inner rail211 may be bolstered by supports 811 of the sleeves 804.

FIG. 9 is an illustration of an embodiment of a leg assembly including awheel lock. A post 904 atop the leg 802 provides for mounting extensionsto the leg 802, enabling the scaffolding to be increased in height. Theleg 802 comprises a casing 906 and a rod 908 mounted within the casing906. A handle 912 is joined to the rod 908. The handle 912 moves withina slot 911, such as a J-slot, and may provide for moving and fixing therod 908 into tension against a spring 902. A worker on the platformassembly 116 may lift and rotate the rod 908 to unlock the wheel 920,then urge the scaffold into a new position. Once in position, the workercan rotate the rod 908 from the fixed position so that the spring 902may urge the rod 908 downward through a guide 914 and an aperture 916 ina caster 918. The caster 918 is coupled to a wheel 920 and isrotationally mounted to the leg 802.

FIG. 10 is a cut away top view illustration of an embodiment of a wheellock. The rod 908 may have a substantially square cross-section. Anaperture 916 in the caster 918 may be formed with eight points, thuspassing the rod 908 as urged by the spring 902 only when the rod 908 isin orientations that align corners of the rod 908 with points of theaperture 916. Once the rod 908 is passed through the aperture 916, thecaster 918 is inhibited from rotating, and the wheel 920 is locked inposition. Furthermore, the rod 908 may contact the wheel 920 in such amanner that the wheel 920 is inhibited from rotating. Thus, in thelocked position, neither the caster 918 nor the wheel 920 maysubstantially rotate.

FIG. 11 is a cut away top view illustration of another embodiment of awheel lock. The aperture 916 comprises sixteen points, thus enabling therod 908 to pass and lock the wheel 920 in twice as many orientations asthe embodiment of FIG. 10.

FIG. 12 is an illustration of an embodiment of an expandable safety railassembly. The safety rail assembly 112 may be mounted on either side tothe platform assembly 116 by inserting the vertical supports 1108 intothe safety rail retainers 214. Gates 1102 may pivot to provideadditional protection from falls. The rail assembly 112 comprises afirst section 1104 formed to slide within a second section 1106 as theplatform assembly 116 is expanded and contracted.

The scaffolding may be rolled into position and expanded or contractedto provide a platform work area of suitable length. A worker may lockthe wheels 920 and climb to the platform assembly 116 using the ladderassembly 114. The wheels 920 may be unlocked, the scaffoldingrepositioned, and the wheels 920 again locked without the workerdismounting the platform assembly 116.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” Words using the singular or pluralnumber also include the plural or singular number respectively.

Additionally, the words “herein,” “above,” “below” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Whenthe claims use the word “or” in reference to a list of two or moreitems, that word covers all of the following interpretations of theword: any of the items in the list, all of the items in the list and anycombination of the items in the list.

1. A scaffold comprising: a plurality of legs; and an expandableplatform assembly supported by the legs, the platform assemblycomprising at least two shelves, at least one of the shelves sliding ina lengthwise direction in relation to the others in a telescopingfashion.
 2. The scaffold of claim 1, further comprising: a first shelfcomprising a first rail; a second shelf comprising a second rail; andthe first rail coupled to slide within the second rail, and the firstshelf coupled to slide under the second shelf.
 3. The scaffold of claim2, further comprising: a rail lock coupled to the outer rail, the raillock comprising a pin and a spring.
 4. The scaffold of claim 2, furthercomprising: the inner rail comprising a flange to support the firstshelf; the outer rail comprising a flange to support the second shelf;and the outer rail comprising a gap through which the flange of theinner rail protrudes.
 5. The scaffold of claim 4, further comprising: atleast one of the flange of the inner rail and the flange of the outerrail comprising a plurality of posts to stabilize at least one of thefirst and second shelves, respectively.
 6. The scaffold of claim 2,further comprising: a transition to alleviate the abruptness of an edgebetween the first and second shelves.
 7. The scaffold of claim 1,further comprising: at least one leg comprising a rod; a spring to urgethe rod through an aperture in a caster and into contact with a wheel;and the aperture formed to pass the rod in limited orientations of therod with respect to the caster.
 8. The scaffold of claim 7, furthercomprising: the rod comprising corners and the aperture comprisingpoints.
 9. The scaffold of claim 7, further comprising: the rodcomprising a handle positioned such that a worker on the platformassembly may use the handle to lift the rod out of contact with thewheel and clear of the aperture.
 10. The scaffold of claim 8, furthercomprising: the rod comprising a substantially square cross section andthe aperture comprising one of eight and sixteen points.
 11. Thescaffold of claim 1, further comprising: an expandable safety rail. 12.A scaffold comprising: at least one leg comprising a rod; a spring tourge the rod through an aperture in a caster and into contact with awheel; and the aperture formed to pass the rod in limited orientationsof the rod with respect to the caster.
 13. The scaffold of claim 12,further comprising: the rod comprising corners and the aperturecomprising points.
 14. The scaffold of claim 12, further comprising: therod comprising a handle positioned such that a worker on the platformassembly may use the handle to lift the rod out of contact with thewheel and clear of the aperture.
 15. The scaffold of claim 13, furthercomprising: the rod comprising a substantially square cross section andthe aperture comprising one of eight and sixteen points.